1. Field of the Invention
The present invention relates to a light-emitting element display device.
2. Description of the Related Art
In recent years, a light-emitting element display device using a self-luminous body, such as an organic light-emitting diode (OLED), is put into practical use. As compared with a related art liquid crystal display device, the light-emitting element display device including an organic EL (Electro-luminescent) display device using the OLED is superior in visibility and response speed, since the self-luminous body is used. Moreover, since an auxiliary illuminating device such as a backlight is not used, further thinning is possible.
JP 2006-276089A discloses an organic EL display device including a PDLC (Polymer Dispersed Liquid Crystal) layer, which is controlled such that the PDLC layer has transparency in a state where a light-emitting element emits light, and the PDLC layer has light-absorbing properties in a state where the light-emitting element does not emit light.
JP 2012-509551A discloses a light-emitting organic electroluminescent element in which a PDLC layer is provided, and inner reflection and cavity effect are reduced by scattering by the PDLC.
The organic EL display device normally includes a reflection film for enhancing light-emitting efficiency at a back side of a light-emitting layer when viewed from an observer. However, when external light is high in, for example, an outdoor place, visibility of an image may be deteriorated by reflection of the external light by the reflection film or rainbow patterns may appear on a screen. Hitherto, in order to prevent the external light reflection, a structure is proposed in which a circular polarizing plate is placed on the upper surface of a display panel. However, the light transmittance of the circular polarizing plate is as low as less than 50%, and the light-emitting efficiency is reduced. Besides, since the addition of the circular polarizing plate adds a new manufacturing process, there is a fear that the manufacturing cost increases.